"""
interface/api/routes/prediction_routes.py
───────────────────────────────────────────
REST endpoints for querying BP prediction history.

Endpoints:
    GET /api/v1/predictions/{user_id}                  — Latest N predictions for a user
    GET /api/v1/predictions/{user_id}/signal/{signal_id} — Prediction for a specific signal

Error handling:
    Domain exceptions bubble up to the global handlers in error_handlers.py.
    EntityNotFoundError is raised explicitly when a lookup returns None.
"""
from __future__ import annotations

from datetime import datetime
from typing import Annotated, Optional

from fastapi import APIRouter, Depends, Query, status

from src.application.dto.prediction_dto import PredictionHistoryResponse, PredictionResponse
from src.application.use_cases.get_prediction_history import GetPredictionHistoryUseCase
from src.domain.exceptions.domain_exceptions import EntityNotFoundError
from src.domain.interfaces.repositories.prediction_repository import PredictionRepository
from src.interface.api.dependencies import (
    get_prediction_history_use_case,
    get_prediction_repository,
)
from src.shared.constants import DEFAULT_PAGINATION_LIMIT
from src.shared.logger import get_logger

logger = get_logger(__name__)

router = APIRouter(
    prefix="/predictions",
    tags=["Blood Pressure Predictions"],
)

# ── Shared error response schemas for Swagger ─────────────────────────────────
_NOT_FOUND_RESPONSE = {
    "description": "Resource not found.",
    "content": {
        "application/json": {
            "example": {
                "error": "not_found",
                "message": "BPPrediction with id='...' not found.",
                "context": {"entity_type": "BPPrediction", "entity_id": "..."},
                "timestamp": "2026-05-31T09:00:00+00:00",
            }
        }
    },
}

_DB_ERROR_RESPONSE = {
    "description": "Database temporarily unavailable.",
    "content": {
        "application/json": {
            "example": {
                "error": "database_unavailable",
                "message": "The database is temporarily unavailable. Please try again later.",
                "context": {},
                "timestamp": "2026-05-31T09:00:00+00:00",
            }
        }
    },
}


@router.get(
    "/{user_id}",
    response_model=PredictionHistoryResponse,
    status_code=status.HTTP_200_OK,
    summary="Get Prediction History for a User",
    description=(
        "Retrieve paginated BP prediction history for a patient. "
        "Optionally filter by date range (ISO 8601 UTC timestamps)."
    ),
    responses={
        200: {"description": "Prediction history retrieved successfully."},
        503: _DB_ERROR_RESPONSE,
    },
)
async def get_prediction_history(
    user_id: str,
    use_case: Annotated[GetPredictionHistoryUseCase, Depends(get_prediction_history_use_case)],
    limit: int = Query(default=DEFAULT_PAGINATION_LIMIT, ge=1, le=500),
    start: Optional[datetime] = Query(default=None, description="Start of date range (UTC ISO8601)"),
    end: Optional[datetime] = Query(default=None, description="End of date range (UTC ISO8601)"),
) -> PredictionHistoryResponse:
    """
    Retrieve BP prediction history for a given user.

    - Without ``start``/``end``: returns the latest N predictions (``limit``).
    - With ``start`` and ``end``: returns predictions within the date range.

    **Possible errors:**
    - `503 database_unavailable` — Supabase is temporarily unreachable.
    """
    logger.info(
        "GET /predictions/%s — limit=%d, start=%s, end=%s",
        user_id, limit, start, end,
    )
    return await use_case.execute(
        user_id=user_id,
        limit=limit,
        start=start,
        end=end,
    )


@router.get(
    "/{user_id}/signal/{signal_id}",
    response_model=PredictionResponse,
    status_code=status.HTTP_200_OK,
    summary="Get Prediction for a Specific PPG Signal",
    description=(
        "Retrieve the AI-generated blood pressure prediction associated "
        "with a specific PPG signal ID."
    ),
    responses={
        200: {"description": "Prediction retrieved successfully."},
        404: _NOT_FOUND_RESPONSE,
        503: _DB_ERROR_RESPONSE,
    },
)
async def get_prediction_by_signal(
    user_id: str,
    signal_id: str,
    prediction_repo: Annotated[PredictionRepository, Depends(get_prediction_repository)],
) -> PredictionResponse:
    """
    Retrieve the BP prediction associated with a specific PPG signal.

    **Possible errors:**
    - `404 not_found` — No prediction exists for the given ``signal_id``.
    - `503 database_unavailable` — Supabase is temporarily unreachable.
    """
    logger.info("GET /predictions/%s/signal/%s", user_id, signal_id)

    prediction = await prediction_repo.get_by_signal_id(signal_id)

    if prediction is None:
        raise EntityNotFoundError(entity_type="BPPrediction", entity_id=signal_id)

    return PredictionResponse(
        id=prediction.id,
        ppg_signal_id=prediction.ppg_signal_id,
        predicted_sbp=prediction.predicted_sbp,
        predicted_dbp=prediction.predicted_dbp,
        predicted_ecg=prediction.predicted_ecg,
        mean_arterial_pressure=prediction.mean_arterial_pressure,
        pulse_pressure=prediction.pulse_pressure,
        hypertension_stage=prediction.hypertension_stage,
        model_version=prediction.model_version,
        inference_time_ms=prediction.inference_time_ms,
        sa_log=prediction.sa_log,
        created_at=prediction.created_at,
    )